- 1612 – Galileo Galilei becomes the first astronomer to observe the planet Neptune, although he mistakenly catalogued it as a fixed star.
- 1895 – Wilhelm Röntgen publishes a paper detailing his discovery of a new type of radiation, which later will be known as x-rays.
- 1972 – Kim Il-sung, already Prime Minister of North Korea and General Secretary of the Workers' Party of Korea, became the first President of North Korea.
Holidays and observances
- Christian Feast Day: